Such shifting devices may be provided with locking devices, which make it possible to change or lock the selector lever position as a function of preset parameters, such as the engine speed, the velocity of the vehicle, the position of the pedal mechanism as well as other conceivable parameters of the vehicle, and are known in various embodiments in the state of the art. The locking devices may be designed as so-called shift locks, which are integrated in the hydraulic control circuit of the automatic transmission corresponding to an exemplary embodiment variant and act such that an electrical control signal dependent on the above-mentioned parameters affects a switching valve, which optionally ignores a change in gear intended by the driver and initiated by the driver via the selector lever until a change in gear will be possible without problems as a consequence of suitable general conditions.
An essential drawback of this is the fact that the shift lock becomes active within the automatic transmission, i.e., the driver is able to bring the selector lever into a position even when the execution of the command thus preset is inadmissible per se and is thus also prevented by the shift lock. As a consequence of the delayed change in gear, driving safety may be impaired in extreme cases when such shift locks are used if the gear shifted finally with a delay is no longer proper for the overall driving situation of the vehicle.
Moreover, there are shifting devices that contain various designs of locking devices, which prevent the undesired or unauthorized selection of a gear or the starting of the engine with a gear engaged by means of mechanical locking elements in the shifting device housing.
Especially the systems known as “keylock” and “shiftlock” may be mentioned here from the state of the art.
In the “keylock” system, the engine can be started only if the selector lever is in the park position “P.” Likewise, when parking the vehicle, the ignition key can be removed in the park position “P” only, so that engagement of the parking brake is compulsory and it is impossible to accidentally remove the ignition key during driving.
In the “shiftlock” system, incorrect shiftings, which may lead to damage to the connected automatic transmission as a consequence of incorrect general conditions for the desired gear selection range, such as excessively high engine speeds or incorrect velocities, are avoided by locking the selector lever. An example of such general conditions is, for example, the specification that the reverse position “R” can only be selected if the velocity of the motor vehicle is lower than 5 km/hour.
For embodying “shiftlock” or “keylock” systems, locking devices are known, e.g., from DE 199 13 005 A1, in which there is a locking element displaceable by the selector lever in a plane in which a meshing contour assigned to the particular gearshift lever position of the selector lever is present, which said contour meshes with a component belonging to the selector lever. The installation of such locking systems is inevitably associated with major interventions with the structure of the shifting device in question, because the contours of the locking element necessary for locking the gear selection range of the selector lever must be adapted to the selector lever geometry.